SPACE.com Gets an Inside Look at Jupiter-Bound Spacecraft

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LITTLETON, Colo. — I've never been so close to something that is
going so far away.

The Jupiter-bound Juno spacecraft is entering a series of vital
tests before its planned liftoff aboard an Atlas V-551 rocket
from Cape Canaveral, Fla., this August — and I got to see it
firsthand. A unique outer-planet spacecraft, the solar-powered
probe is slated to reach the giant planet in July 2016.

Juno will map
Jupiter's intense magnetic field, investigate the existence
of a solid planetary core, measure the amount of water and
ammonia in the deep atmosphere, and observe the planet's auroras.
The Juno mission is the second spacecraft designed under NASA's
New Frontiers Program.

Here at Lockheed Martin Space Systems, the builder of Juno, the
intricate spacecraft is getting a good and appropriate dose of
tender loving care – something it will need when it encounters
the intense radiation at Jupiter.

This reporter climbed into a "bunny suit" (why it's called that,
I haven't a clue, as it takes forever to hop into one) — the
required clothing to get up close and personal with the probe.

Waddling forward, I was greeted and comforted by similarly
smocked Jack Farmerie, Lockheed Martin's lead spacecraft
technician on the
Juno mission to Jupiter. He's clearly proud of his job, one
element of which is figuring out where to route boa
constrictor-like cabling and wiring harnesses that snake
throughout Juno.

"Do you dream of cabling?" I asked Farmerie.

"I kinda do. I've had some bad dreams on occasion," the
technician responded, and said that he sometimes spends 10 to 12
hours a day just putting spacecraft connectors on — each one
enclosing some 150 individual wires.

Farmerie pointed to wiring harnesses all over Juno that are
treated specially with copper overwrap. "That provides enough
shielding from Jupiter's radiation … so the wiring will survive
that environment. But that adds a lot of weight."

Special attention is also given to assuring everything on Juno
has the same ground potential — that is, avoiding electrical
charging that could arc from one spot to another on the probe.
"That would be detrimental to the science," Farmerie said.

Juno is outfitted with a trio of huge solar arrays. The
spacecraft benefits from advances in solar cell design with
modern cells that are 50 percent more efficient and radiation
tolerant than the silicon cells available for space missions 20
years ago.

Vaulting to Jupiter

Juno will fly a highly elliptical polar orbit around the giant
planet. That avoids most of
Jupiter's high-radiation regions. It does so by approaching
over the north, dropping to an altitude below the planet's
radiation belts and then exiting over the south.

Nevertheless, Juno features the first radiation-thwarting
electronics vault — a uniquely crafted titanium box that protects
key components from exposure to the heavy radiation environment
at Jupiter.

"The goal was, anything that we could fit inside the vault … we
did," Farmerie told SPACE.com. "It was definitely the toughest
wiring job I've had so far."

Other "out of the box" items that dot Juno's structure have their
own built-in shielding. Germanium-coated blankets are used to
help counter whatever Jupiter throws at the spacecraft, he said,
as are conductive Kapton film wraps.

All in all, my intuition is that Juno carries nothing from Home
Depot or any other general hardware store.

"We have this thing called traceability," Farmerie said. "Every
screw, every washer, every tiny little thing on this spacecraft
can be traced back to the day we bought it and where it came
from."

Juno is being prepared for a set of tests to showcase its
readiness to travel onward to Jupiter — and the August liftoff
date is creeping up.

"It's a line in the sand," Farmerie advised. "We do what we have
to do to get to the launch pad on time. Usually that equates to
overtime. It's a way of life for us."

Harsh environment

Tour of Juno over, back out of the airlock, I quickly shed my
space-age coveralls to talk with Tim Gasparrini, Lockheed Martin
program manager for Juno.

"Jupiter is a harsh place to go … terrible radiation and you've
got the charged- particle environment you have to worry about,"
Gasparrini told SPACE.com. "It's much more severe than
designing a Mars mission."

Contrasting Juno to other spacecraft Gasparrini has worked on:
"It's bigger, and with bigger come harder," he said.

Juno totes 25 sensors and nine experiments. "That's a lot of
stuff. Lots of fields of view for all those instruments and lots
of things that you have to keep happy," Gasparrini added.

While in orbit at Jupiter, the spinning spacecraft will sweep the
fields of view of its instruments through space once for each
rotation. At three rotations per minute, the instruments' fields
of view cut across Jupiter about 400 times in the two hours it
takes to fly from pole to pole.

Juno will orbit Jupiter 32 times, skimming to within 3,000 miles
(4,800 kilometers) above the planet's complex cloud tops, for
roughly one year. After that, it is to be de-orbited to avoid
smacking into and
contaminating one of the Jovian moons.

Degrees of difficulty

As Juno's takeoff time to Jupiter draws closer, Gasparrini
underscored the pressure to get the probe ready for departure.
The drumbeat of several critical evaluations of the completed
spacecraft is palpable.

"You have this constant tension between mission success and a
21-day launch window," Gasparrini said. "You're doing everything
you can to make sure that the spacecraft operates 100 percent
flawlessly when it gets on orbit. But you have this realization
and reality that you've got 21 days to get it off the planet, and
that we're not doing anything foolish or shortsighted that we
regret later on."

Every spacecraft is different, Gasparrini concluded, each
coughing up degrees of difficulty.

"You go in thinking 'this is going to be the easy one'… and it's
never like that," he said. "They all have their own challenges.
That's why we do this … because it is challenging and it's
exciting."

Leonard David has been reporting on the space industry for
more than five decades. He is past editor-in-chief of the
National Space Society's Ad Astra and Space World magazines and
has written for SPACE.com since 1999.